Sudden cardiac death remains the major medical problem in the United States. Most victims of sudden cardiac death die of ventricular fibrillation, most commonly associated with coronary artery disease. Resuscitated survivors of ventricular fibrillation have a high risk of recurrence of ventricullar fibrillation. Epidemiologic studies of survivors of ventricular fibrillation have allowed a precise stratification of risk or recurrence of ventricular fibrillation. Patients at high risk of recurrence are candidates for therapy to reduce their risk. This project is designed to compare the efficacy of amiodarone, a promising new antiarrhythmic agent to conventional antiarrhythmic therapy in patients who have survived one episode of out-of-hospital ventricular fibrillation and who are at high risk (= 20% risk of recurrence within 1 year). Patients will be entered into the study for random assignment to amiodarone or to conventional antiarrhythmic agents. Drug dosage will be adjusted according to electrocardiographic monitoring, serum drug levels, EP testing and symptoms. The project will attempt to identify whether treatment with amiodarone and conventional antiarrhythmic agents (quinidine, procainamide, disopyramide, mexiletine, flecainide or tocainide) yields equivalent survival, equal suppression of ambient ventricular arrhythmias, equal patient tolerance and toxicity, equal hospitalization time, cost of care, and equal symptoms of arrhythmias. An extensive data base will be managed by members of the Coordinating Center for the Coronary Artery Surgery Study (CASS) and the Cardiac Arrhythmia Pilot Study (CAPS), with a well-established statistical/data management system. A pilot study has been performed to explore the feasibility of this program. In 1.5 years with only a part-time nurse, 108 patients have been identified and evaluated, with 59 patients eligible and 53 patients enrolled in the study. Thus far, with a mean of less than 1 year followup there have been 12 deaths, 10 of these sudden. This study will be unique because of the ability to randomize a group of high risk survivors of ventricular fibrillation. Using this high risk patient population will allow the evaluation of the efficacy of prescribed therapy while using a relatively small number of patients.